Warren is vulnerable, she’s not as popular as most think. There’s a pretty sizeable slice of the electorate (I’d guess 35%) who can’t stand her. Having said that Diehl has no shot (he was trump co-chair in 16, and Trump is not popular at all in Mass.) the person with the best shot at Stormy is Beth Lindstrom who is running against Diehl in the GOP primary on Sept 4. Don’t get me wrong, I like Diehl, was with him on the gas tax repeal a couple of years ago, but Warren would easily overwhelm him (trump ties, going after a woman...) Beth has a shot, not a good one, but the only realistic one at Warren.
Which means 65% of the electorate can stand her. No way she loses.